Recently, the development of planar display panels such as a plasma display panel, a field emission display panel, a fluorescent display tube, a liquid crystal display device, an electroluminescence display panel, and a light emitting diode display panel has rapidly been made. Of these planar display panels, the plasma display panel is a display panel capable of displaying by allowing plasma discharge to occur between an anode electrode and a cathode electrode facing each other in a discharge space disposed between a front glass substrate and a rear glass substrate, and irradiating a phosphor provided in the discharge space with ultraviolet rays generated from a discharge gas sealed in the discharge space. The gas discharge type display panel such as a plasma display panel or a fluorescent display tube requires an insulating barrier rib to partition a discharge space. Also, the field emission type display panel requires an insulating barrier rib to separate a gate electrode from a cathode electrode.
Also in the medical field, a member including a barrier rib has attracted attention. Heretofore, an analogue type radiographic apparatus using a film has widely been used in medical practice. However, digital type radiographic apparatuses such as a computed radiography system and a planar X-ray detector have recently been developed. In the planar X-ray detector, a scintillator panel capable of changing radiations into visible rays by an X-ray phosphor is used. However, there is a problem such as low S/N ratio because of scattering of light emitted by the X-ray phosphor. Thus, there has been proposed a method in which an X-ray phosphor is partitioned by a barrier rib, thereby suppressing light scattering.
There have been known, as a method of forming these barrier ribs, a screen printing method in which a barrier rib paste is repeatedly applied to form a pattern by a screen printing plate, followed by drying and further firing, a sand blasting method in which masking is applied on a layer of a dried barrier rib material using a resist, followed by shaving through a sand blasting treatment and further firing, a mold transfer method (imprinting method) in which a mold with a pattern is pressed against a coating film of a barrier rib paste to form a barrier rib pattern, followed by firing, a photosensitive paste method (photolithographic method) in which a barrier rib material composed of a photosensitive paste material is applied, followed by drying, exposure, a developing treatment and further firing, and the like. All these barrier rib-forming methods are methods in which a barrier rib pattern is formed using a paste containing a low-softening point glass powder and an organic component, and then the organic component is removed by firing to form a barrier rib which is an insulating pattern containing the low-softening point glass. Of these methods, the photosensitive paste method is a method capable of realizing high definition and a large area, and is a method with high cost merit.
In a conventional barrier rib formation method, a barrier rib pattern is formed using a barrier rib paste containing a low-softening point glass powder and an organic component, followed by firing to form a barrier rib, thus leaving a carbon residue in the barrier rib after firing. When a large amount of this carbon is left, the barrier rib causes coloration, leading to a decrease in reflectance, thus causing a problem that an adverse influence is exerted on display characteristics such as luminance, and reliability.
Therefore, to produce a member including a barrier rib such as a high-reliability planar display panel or scintillator panel, the member being excellent in display characteristics such as luminance, there have been proposed various techniques capable of reducing a carbon residue after firing (Japanese Unexamined Patent Publication (Kokai) No. 2001-305729, Japanese Unexamined Patent Publication (Kokai) No. 2008-50594 and Japanese Unexamined Patent Publication (Kokai) No. 11-52561). Japanese Unexamined Patent Publication (Kokai) No. 2001-305729 uses, as an organic component in a barrier rib paste, a resin having a hydroxyl group and a polymerizable unsaturated group, for example, a polyol which is excellent in pyrolytic properties at high temperature. Japanese Unexamined Patent Publication (Kokai) No. 2008-50594 uses, as an organic component, an acrylic copolymer including a polyalkylene oxide segment having a high content of oxygen atoms to enhance pyrolytic properties of the organic component. Japanese Unexamined Patent Publication (Kokai) No. 11-52561 uses a low-softening point glass having a glass transition point, which is 10° C. or higher than the temperature at which the reduction ration of the organic component reaches 80%, so that a decomposition product of the organic component is not left in glass.
However, in these conventional techniques, it is impossible to reduce a carbon residue caused by poor pyrolytic properties which appear as a result of the reaction of an organic component with components in glass in a barrier rib paste or the barrier rib pattern formation step, leading to insufficient reduction of the carbon residue in a barrier rib. Thus, it could be helpful to provide a barrier rib paste excellent in pyrolytic properties of an organic component upon firing, and capable of forming a barrier rib which contains less carbon residue after firing and also has high reflectance. It could also be helpful to provide a member including a barrier rib such as a high-reliability planar display panel or scintillator panel, the member including a barrier rib which contains less carbon residue and also has high reflectance, and also being excellent in display characteristics such as luminance.